Part passing FEA but failing lab test
Part passing FEA but failing lab test
(OP)
I am designing brake pedal.
Its made of plastic, I am using CATIA/ANSYS for FEA analysis.
Part is within stress limits and sress counters are under yield stress, but during lab test, it fails.
I think that I am not modeling plastic correctly in FEA, I am using non linear model.
Any Ideas?
Its made of plastic, I am using CATIA/ANSYS for FEA analysis.
Part is within stress limits and sress counters are under yield stress, but during lab test, it fails.
I think that I am not modeling plastic correctly in FEA, I am using non linear model.
Any Ideas?






RE: Part passing FEA but failing lab test
Have you verified the parts being tested are made correctly?
Have you verified the test is being conducted correctly?
You may want to ask the FEA question in the relevant software forum, or maybe in one of the structural analysis ones.
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Part passing FEA but failing lab test
The difference between manufacturer's data and "as moulded" figures can be very vast. As KENAT implied (amongst other things) - check the moulding conditions:
e.g.
Has the material been dried correctly (if required)?
Is the mould temperature high enough to attain maximum crystallinity?
Plus a myriad others. Best bet is to get material manufacturers on site to witness the moulding process.
H
www.tynevalleyplastics.co.uk
RE: Part passing FEA but failing lab test
Chris DeArmitt PhD FRSC CChem
www.phantomplastics.com
Consultant to the plastics industry
RE: Part passing FEA but failing lab test
Non optimal moulding conditions.
Use of lab test piece data as opposed to real world design re load sharing.
Glass fibre orientation.
Part is not made to exact same dimensions as model, especially re sharp edges and radii.
A different grade may have been used for data production.
After moulding conditioning.
Data measured at a standard section thickness is not reliable at a different thickness due to changes in crystallinity at different depths into the plastic and different glass orientation at different thickness. This is sometimes called skin layer effect.
What material. What section thickness, what after treatments, what rib thickness and rad on ribs to beam junction.
Regards
Pat
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